This invention relates to a method and device for the authentication and certification of documents.
Some printed documents such as birth certificates, academic records, bonds, legal documents amongst others are sometimes altered as part of an illegal activity.
A method of authenticating printed documents is disclosed in U.S. Pat. No. 5,544,045. This U.S. patent discloses an authenticating scheme whereby an original document is scanned and then encoded according to a predetermined coding algorithm into a unique digital code, which is then printed as a bar code together with the original image on a new document. Authentication of the new document is achieved by scanning the new document to produce a new code and then comparing the new code with the printed code on the new document. A match indicates the new document is an authentic copy of the original. A mismatch indicates the document has been altered and is not authentic.
The above method suffers from the disadvantage that persons may circumvent the method by obtaining the coding algorithm, altering the image, then encoding the altered image to obtain a new code and replacing the old printed code with the new code.
According to one aspect of the invention, there is provided a certifier device for producing a certified document of an original document, the certifier device including: scanning means for scanning the original document to generate a true copy image of the original document; encoding means for computing a digital code which is representative of the true copy image; encryption means for encrypting the digital code according to a private key associated with a certifier identification; compositing means for compositing an image including the true copy image together with the encrypted digital code and certifier identification.
According to another aspect of the invention, there is provided a certified document including; a true copy image of an original document; a certifier identification; an encrypted digital code, wherein the encrypted digital code is representative of the true copy image and which has been encrypted by a private key associated with the certifier identification.
According to another aspect of the invention, there is provided a verifier device for verifying a certified document, the certified document including a true copy image of an original document; a certifier identification; an encrypted digital code, wherein the digital code is representative of the true copy image and which has been encrypted by a private key associated with the certifier identification, the verifier device including: scanning means for scanning the certified document; decryption means for decrypting the encrypted digital code according to a public key associated with the certifier identification; encoding means for computing a digital code which is representative of the true copy image; and comparator means for comparing the digital code supplied by said encoding means and said decrypted digital code supplied by said decryption means; wherein a match of the digital codes indicates the certified document is authentic and a mismatch indicates the document is not authentic.
According to another aspect of the invention, there is provided a method of producing a certified document of an original document, said method including the steps of; scanning the original document to generate a true copy image of the original document: computing a digital code which is representative of the true copy image; encrypting the digital code according to a private key associated with a certified identification; and compositing an image including the true copy image together with the encrypted digital code and certifier identification.
According to another aspect of the invention, there is provided a method of verifying a certified document, the certified document including; a true copy image of an original document; a certifier identification; an encrypted digital code, wherein the digital code is representative of the true copy image and which has been encrypted by a private key associated with the certifier identification, said method including the steps of: scanning the certified document; decrypting the encrypted digital code according to a public key associated with the certifier identification; computing a digital code which is representative of the true copy image; and comparing the said decrypted digital code and said computed digital code: wherein a match of the digital codes indicates the certified document is authentic and a mismatch indicates the document is not authentic.